Electromagnetically operable electric switches



April 21, 1959 Y T. cuRzoN 2,333,433

ELECTROMAGNETICALLY OPERABLE ELECTRIC SWITCHES Filed Oct. 17, 1957 2 Shets-Sheet 1 Fig.3

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I ELECTROMAGNETICALLY OPERABLE ELECTRIC SWITCHES Filed Oct. 17, 1957 2 Sheets-Sheet 2 Fig.7

I Ire/vamp T. Ccbpzrz/ ELECTROMAGNETICALLY OPERABLE ELECTRIC SWITCHES Thomas Curzon, London, England, assignor to C. A. V. Limited, London, England Application October 17, 1957, Serial No. 690,843

Claims priority, application Great Britain October 22, 1956 3 Claims. (Cl. ZOO-Q4) This invention relates to the electromagnetically operable switches of the kind commonly known as cut-outs used on vehicle or like electrical installations for automatically connecting or disconnecting a dynamo to or from a storage battery at predetermined dynamo speeds. A cut-out for such purpose ordinary comprises an electromagnet provided with a winding to be connected in parallel with the dynamo, and a second winding to be connected in series with the battery, the electromagnet serving to actuate a spring-loaded armature associated with the contact pieces of the switch.

The object of the present invention is to provide a cutout of improved construction whereby opening and closing of the switch is effected by a snap action.

A cut-out in accordance with the invention includes a spring blade attached to an armature and carrying the movable contact piece or pieces, the said blade being gapped, and shaped to form therewith a bowed tongue piece, and a pair of fulcrum pieces for supporting respectively one end of the blade and the free end of the tongue piece, the arrangement being such that the tongue piece is held in a stressed condition, and when the blade is moved at least a part of its movement is effected suddenly under the action of the tongue piece.

In the accompanying drawings:

Figure 1 is a part sectional side elevation, Figure 2 a rear elevation, and Figure 3 a plan of a cut-out embodying the invention. Figure 4 is a front elevation of the spring blade.

Figure 5 is a fragmentary sectional side elevation, Figure 6 a rear elevation, and Figure 7 a section on the line 7, 7 of Figure 5, illustrating an adjustable stop for regulating the action of the cut-out.

Referring to Figures l-4, the frame part of the cut-out consists of an iron strip bent to an L-shape forming a pair of limbs ab. To the limb a is secured an iron core 0 which is parallel with the other limb b and on which are mounted the usual windings d. The said other limb b hereafter referred to as the fulcrum post has its free end bent over at right angles towards the core to serve as a fulcrum piece 2, this piece having formed on its outer surface a transverse notch. At a convenient distance from this fulcrum piece, the post is slit to enable a second fulcrum piece 1 to be pressed outwardly from it parallel with the first, the second fulcrum piece being transversely notched at its underside. Near the junction of the post with the other limb a of the frame is secured an electrically insulated contact piece g and associated circuit terminal h. Also a second contact piece is secured directly to the limb b. Alternatively the second contact piece may be insulated from the said limb and secured to a terminal in a similar manner to the first contact piece.

The armature consists of an inverted L-shaped piece of iron to one limb j of which is secured the spring blade to be hereafter described, the other limb k being adapted to extend over the free end of the magnet core 0.

The spring blade in is formed from a rectangular metal plate as shown in Figure 4, and is gapped so that it can nited States Patent 0 2,883,488 Patented Apr. 21, 1959 be hung on the fulcrum piece e. Also the gapped portion is shaped to provide a resilient tongue piece n the free end of which can be engaged with the second fulcrum piece 1. The plate is secured by rivets 0 (Figure l) to the part j of the armature, and at its free end it has secured to it a pair of contact pieces corresponding to the fixed contact pieces above mentioned. Only one of the contact pieces on the blade appears in Figure 1 and this is indicated by p. The two contact pieces on the blade are interconnected by a bar q of copper or other metal of high electrical conductivity.

For enabling adjustment to be effected of the electromagnet force required to actuate the armature in the direction for closing the associated circuit, an adjustable stop is provided as shown in Figures 5-7. The stop consists in part of a screw r secured to the limb b of the frame between the contact pieces, and on the inner end of the screw is formed a head s which can abut against the side of the blade m remote from the contact pieces. The lower edge of the blade is gapped to accommodate the screw, and the bar q is arched as shown in Figure 7 to accommodate the head s of the stop. Adjustment of the position of the head of the stop is effected by imparting an appropriate rotation to the screw.

The tongue piece It on the blade m is initially strained by bending it to a shallow arcuate form as shown in Figure l, and is held in this condition by its engagement with the notch in the second fulcrum piece e.

When the blade is mounted in position on the fulcrum post the strained tongue piece it exerts a force which tends to move the blade away from the post to an extent determined by the stop.

The limb j of the armature to which the blade is attached is made of such length that its free end can exert a lateral pressure on the blade at a position slightly below the free end of the tongue piece It as shown in Figure 1. Also it is forked so that this pressure is applied only to the side parts of the blade which flank the tongue piece. Moreover, it is slightly bowed to enable the position at which its free end touches the blade to be definitely located.

The arrangement is such that the cut-out is held in its open position by the strained tongue piece. When the electromagnet is energised for closing the cut-out, the first elfect is to move the main part of the blade relatively to the tongue piece, until a position is reached at which the force exerted on the blade by the tongue piece can over-ride the action of the electromagnet and complete the movement of the blade suddenly. When the exciting current of the electromagnet falls below a predetermined amount the force exerted on the blade by the tongue piece causes the blade to be returned to the open position suddenly.

The invention is not, however, restricted to the foregoing example, as subordinate details of design or construction may be varied provided always that the sudden closing and opening of the cut-out is effected by the action of a spring blade acting substantially as above described.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. An electromagnetically operable electric switch of the kind specified, comprising in combination an electromagnet, an armature movable by said electromagnet, a pair of fulcrum pieces, a fixed support from one side of which said fulcrum pieces extend in parallel and spaced relationship, a spring blade in the form of a metal plate to one end portion of which said armature is secured, and which has formed therein a gap shaped to accommodate said fulcrum pieces, and to provide said blade with a resilient tongue piece extending towards said end portion, at least one contact piece on the other end portion of said spring blade, and at least one fixed contact piece into and out of contact with which the first mentioned contact piece is movable by said spring blade, the latter being in pivotal engagement at one end of the gap therein with one side of one of said fulcrum pieces, and said resilient tongue piece being stressed into a bowed condition in which it is retained by pivotal engagement of its free end with the opposite side of the other of said fulcrum pieces, whereby movement of said armature has the initial effect of moving a part of said spring blade 'relatively to said resilient tongue piece until a position is reached in which the force exerted on said blade by said tongue piece causes said blade to effect sudden movement of the contact piece thereon.

2. An electromagnetically operable switch according to claim 1, in which said armature consists of a pair of angularly spaced limbs one of which extends across one end of said electromagnet, and the other of which is secured to said spring blade, the last mentioned limb of said armature being forked and of such length that its free end can act on said blade at opposite sides of said tongue piece and at positions slightly nearer to the contact piece on said blade than the free end of said tongue piece.

3. An electromagnetically operable switch according to claim 1, and having an adjustable stop forming an abutment for said spring blade at a position adjacent the contact piece thereon, and thereby serving to determine the initial position of said blade.

References Cited in the file of this patent UNITED STATES PATENTS 2,246,724 Eaton June 24, 1941 2,487,372 Rackley Nov. 8, 1949 2,490,020 Enzler Dec. 6, 1949 2,753,416 McClain July 3, 1956 

